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Call for ContributionsHETEROCYCLES Special Issue Vol. 99 in honor of Professor Tohru Fukuyama on 70th Birthday

Submission deadline: September 10, 2018
On the occasion of Professor Tohru Fukuyama's 70th birthday, HETEROCYCLES editorial office is planning to publish special anniversary issue on April 1, 2019 as Vol. 99. Authors are invited to submit their work to this topical issue.
Authors wishing to submit their manuscript should contact editorial office via e-mail by the end of May, 2018. Manuscript should reach the editorial office no later than September 10, 2018.
Contact: submit@heterocycles.com

March 5, 2018

Heterocycles Award
HETEROCYCLES is pleased to announce Heterocycles Award.
In recognition of an outstanding oral presentation at the 47th Congress of Heterocyclic ChemistrySee more

December 13, 2017

Call for ContributionsHETEROCYCLES Special Issue Vol. 97 in honor of Professor Kiyoshi Tomioka on 70th Birthday

Submission deadline: February 15, 2018
On the occasion of Professor Kiyoshi Tomioka's 70th birthday, HETEROCYCLES editorial office is planning to publish special anniversary issue on September 1, 2018 as Vol. 97. Authors are invited to submit their work to this topical issue.
Authors wishing to submit their manuscript should contact editorial office via e-mail by the end of November, 2017. Manuscript should reach the editorial office no later than February 15, 2018.
Contact: submit@heterocycles.com

Abstract

A number of 1-aryloxymethyl-3H-pyrano[2,3-c]quinolin-5(6H)-ones (1a-h) on heating in N,N-diethylaniline for 8 h afforded 1-aryloxymethyl-2-methyl-furo[2,3-c]quinolin-4(5H)-ones (2a-h) in 66-79 % yields.

■ New Syntheses of 4(5)-Aryl-5(4)-(2-chromonyl)-1,2,3-triazoles from 2-Styrylchromones and Sodium Azide

Abstract

The reactions of 2-α-bromostyrylchromones or 2-styrylchromones with sodium azide afforded 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles. In the case of 2-α-bromostyrylchromones, the unexpected 1-aryl-5-(2-chromonylmethyl)tetrazoles have been obtained as minor products and the mechanism of its formation is discussed. The bromination/dehydrobromination reactions of 2-styrylchromones were also studied.

Abstract

Stannyl radical addition-cyclization of the isolated oximeethers or α,β-unsaturated oxime ethers connected by a tether to α,β -unsaturated aldehydes or ketones provides a new entry to the adjacently functionalized heterocycles.

Abstract

Methylenebis(4-hydroxy-2-pyrone) or methylenebis(4-hydroxy-coumarin) derivatives (5) have been synthesized from 4-hydroxy-2-pyrones (6) and (8) or 4-hydroxycoumarine (10) with aldehydes (4) in the presence of diethylaluminum chloride.

Abstract

The reaction of enolates of 1,3-dicarbonyl compounds (1) with 3,4-dibromo-2-butanone(2) afforded hydrofuran derivatives (4) or (5) in the presence of DBU in THF and the reaction was applied to the one-pot synthesis of antitumor naphthofuran natural products (29).

Abstract

C-12b Methyl substituted indolo[2,3-a]quinolizidines possessing different structural features were prepared as model compounds to investigate whether different roxburghine alkaloids can be obtained by acid-catalysed epimerization. When they were subjected to epimerization under strongly acidic conditions (TFA), indoloquinolizidines (7) and (8) and lactams (12) and (13) epimerized as expected but the vinylogous urethanes (4) and (5) remained unaffected. The results indicate that the mechanism starting with protonation at the β-position of indole (Mechanism 1) is active in the acid-catalysed epimerization of vinylogous urethanes. This further suggests that roxburghine alkaloids do not epimerize at C-19.

Abstract

The dithiane (6) was synthesized by bromine oxidation of the dithiol (5), despite the significant steric strain in the pentacyclic system. In the presence of elemental sulfur the oxidation of 5 gave selectively the 1,2,3-trithiacycloheptane (7), while from the diastereomeric dithiol (4) under the same conditions the 1,2,3,4-tetrathiacyclooctane (8) was obtained in good yield. The geometry of the molecules was determined by X-Ray analysis.

Abstract

Cyclohexa-1,2,3-triene was generated in the presence of N,α-diphenylnitrones to form seven-membered cyclic amines via piradone derivatives, which were formed through [4+2] type cycloaddition of the central double bond of cyclohexa-1,2,3-triene with nitrones.

Abstract

The new reductive alkylating agent, 2-(4-chloromethylstyryl)-1-methyl-5-nitro-1H-imidazole gives exclusively O-alkylation with 2-nitropropane anion. The electron-transfer C-alkylation is observed with the anions of ethyl 2-nitro-propionate and dialkyl α-substituted malonates. The competition between C- and O-alkylation reactions depends on the nature of the nucleophile because of the low rate of decomposition of the radical anion of the alkylating agent.

Abstract

1-Methyl-3,6,8-trinitro-2-quinolone shows high reactivity compared with 1-methyl-3,6-dinitro-2-quinolone. It was found the 8-nitro group activates a 2-quinolone ring sterically rather than electronically.

Abstract

A simple one-step synthesis of azabicyclic peroxides was achieved by the manganese(III)-mediated oxidative formal [2+2+2] cycloaddition. The reaction of alkenes (1) with pyrrolidinediones (2) was carried out with manganese(III) acetate in acetic acid at 23 °C under a dry air stream to give 1-hydroxy-8-aza-2,3-dioxabicyclo[4.3.0]nonan-7-ones (3) in good to quantitative yields. Similar reactions at elevated temperature gave 3-ethyl-2,4-pyrrolidinediones (4) and/or 3-ethenyl-2,4-pyrrolidinediones (5) in good yields.

■ Chemoenzymatic Enantioselective Synthesis of (-)-Indolizidine 167B

Abstract

(5R, 9R)-(-)-Indolizidine 167 B was synthesized in 8 steps from N-benzyloxycarbonyl-cis-2(R)-acetoxyrnethy1-6(S)-hydroxymethy1piperidine (2) in an overall yield of 60%. This starting material was obtained from enzymatic desymmetrization of the corresponding meso diacetate (1).

■ The Preparation and Lead Tetraacetate Oxidation of Mixed Bisaroyl Hydrazones of Biacetyl to 1-(α-Aroyloxyarylideneamino)-3,5-dimethyl-1,2,3-triazoles

Abstract

The preparation and lead tetraacetate oxidation of the mixed aroyl hydrazones of biacetyl (2) to the pairs of isomeric 1-(α-aroyloxy-arylideneamino)-3,5-dimethyl-1,2,3-triazoles (6) and (6’) is described. The product ratio of 6/6’ is evaluated in terms of the stability imparted to the zwiterionic intermediate (5) by the different substituents on the aroyl groups.

Abstract

A new trans-clerodane lactone, conyzalactone, together with six known compounds, was isolated from the aerial parts of composite Conyza blinii. Its structure was elucidated on the basis of extensive NMR analysis and X Ray crystallographic data.

Abstract

Various 3-aryl-3a,4,5,6,7,7a-hexahydro-1,2-benzisoxazol-4-ones were methylated at 3a-positions and reduced by NaBH4 to afford the corresponding 3a,4-cis-3a,7a-cis-3a-methyl-3a,4,5,6,7,7a-hexahydro-1,2-benzisoxazo1-4-ols with excellent diastereoselectivity. The resulting hexahydro-1,2-benzisoxazol-4-ols were easily converted to the corresponding 2-aroyl-2-rnethylcyclohexane-1,3-diols by catalytic hydrogenation with Raney Ni.

■ Conformational Study of Geissoschizine Isomers and Their Model Compounds

Abstract

Study was made of the major factors affecting the conformational equilibrium between the C and D rings of geissoschizine isomers (1-4) and several of their model compounds (5-24). Conclusions are mainly based on 13C NMR data.